The accumulating conveyor of my application Ser. No. 761,584, now U.S. Pat. No. 4,598,818 employs a pair of multiple strand roller chains operatively trained about paired end sprockets for coordinated movement along an endless path having horizontal upper and lower ones extending between the end sprockets. Run strand of each roller chain is operatively trained about one set of end sprockets while a second strand of each chain is suppported laterally clear of the end sprockets and track means employed to support and guide the chains along their upper and lower runs. A plurality of article carriers are mounted to extend between the two chains and to be supported from the second strands of the chains by outer and inner support plates fixedly mounted at the opposite sides of each carrier. The outer support plates support the carriers upon the chains during transit of the upper run while the inner support plates suspend the carriers in an inverted position during transit of the lower run by the frictional engagement of chain engaging edges on the plates with the chain rollers. The chain is continuously driven and, because of the frictional coupling between the carriers and chains, carriers may be accumulated or held stationary by suitable stops at selected locations along either the upper or lower run.
To transfer carriers around the curved portions of the chain path defined by the end sprockets, the spacing and configuration of the opposed edges of the inner and outer support plates are designed to automatically positively couple the carrier to the chain as the carrier moves from the upper or lower run into the curved portions of the chain path.
The length of the straight edge section of the inner plate, its spacing from the opposed straight edge section of the outer plate, and the inclination of the beveled edge sections of the inner plate are related to the end sprocket radius and the pitch of the chain in a fashion such that when the carrier moves onto the curved portions of the endless path defined by the end sprockets, the corners at the junctures of the straight edge section and beveled edge sections of the inner plate project into the spaced between two adjacent rollers of the chain and are positively held in this position by the tangential engagement of the straight edge of the outer plate with a roller midway between those two sets of rollers engaged by the inner plate. This action provides a positive coupling between the carrier and the chain as the carrier transits the curved portions of the endless path so that the carriers can be transported from the lower run upwardly around one set of end sprockets to the upper run and be restricted to movement with the chain as the carrier is passed downwardly around the other end sprockets from the upper run to the lower run.
The driving or restraining force exerted by this coupling is exerted between the surface of a chain roller and the flat beveled edge surface of the inner plate which tangentially engages the surface of the roller at an angle such that only a relatively small extent of the beveled edge projects into the curved path of movement of the roller. The configuration of the support plates is designed on the assumption that the chain rollers will accurately follow the curved path defined by the end sprockets and in order to cooperate with the chain engaging edges of the support plates, the second strands of chain which these plates engage cannot directly engage the end sprockets. Further, adherence of the chain to the curved path defined by the sprockets requires the maintenance of a minimum chain tension. After prolonged usage, particularly where relatively heavy carriers are involved, distortion of the unsupported second strand of chain to the point where the coupling between the chain and carrier is lost during transit of the end sprockets has occurred.
The present invention overcomes this problem.